The present invention relates to a solution purification method for an electrolyte. More specifically the invention relates to a method of performing washing with sulfuric acid, elution and washing with water with respect to a chelate resin, when substances contained as impurities in a copper electrolyte used in an electrolytic copper refinery, specifically Sb and Bi are recovered using the chelate resin while the copper electrolyte is purified.
If the concentration of impurities in the V group such as Sb, Bi exceeds a certain level in the electrolyte in copper electrolysis, the quality of an electrolytic copper as a product deteriorates, requiring solution purification of the electrolyte.
As one of these solution purification methods, there is a method of bringing the copper electrolyte into contact with a chelate resin which adsorbs Sb and Bi to thereby adsorb these. The method, normally known as the most common method for this, comprises the steps where a chelate resin is filled into one column in an amount corresponding to a required quantity to be removed, to adsorb Sb and Bi by feeding the copper electrolyte thereto, and after the chelate resin has been washed with water and then with sulfuric acid or the like which is substituted for the electrolyte, the chelate resin is brought into contact with an eluent.
When only one column is used for the operation, however, since the adsorption and elution operations are required alternately, and the solution feed rate and the time required for feeding are different for each operation, at least two columns must be prepared for continuous removal.
The removal quantity of the V group impurities is different according to the quality of impurities in the V group in the copper electrolyte anode, the eluted amount and the standard control concentration. In a normal electrolytic copper refinery, the removal quantity becomes several tons per month. These impurities in the V group are normally removed by electrolyte for removing copper in electrolytic drainage. If they are removed by using a chelate resin, several m3 units of resin are required.
Moreover, with a conventional method using a chelate resin, the amount of the processing solution in the washing and elution processes increases/decreases according to the amount of resin, and the amount of the processing solution increases with the increase of the amount of resin. Hence, the solution storage tank or the like becomes large, and even if the operation for each processing is simple, there is a problem in that the equipment becomes large. Moreover, there are another problems in that pressure loss increases with an increase in the size of the column, and that the fed liquid flows in the column unevenly, thereby making it difficult to adsorb and elute a predetermined amount.
Moreover, if a required amount of the processing solution is fed in the washing and elution process, a low concentration solution is generated in a large quantity.
On the other hand, if the quantity of the processing solution is reduced, washing is insufficient, and there is a problem in that in the elution process thereafter, Cu may be mixed into the eluate flowing out of the chelate resin, or the eluate may be mixed into the copper electrolyte in the adsorption process. Hence, the quantity of the liquid to be fed cannot be reduced. Moreover, if the quantity of the processing solution is reduced, the peak concentration at the time of elution becomes only several grams/liter.
Therefore, an object of the present invention is to provide a solution purification method to achieve efficient removal of impurities, reduction of the processing solution and down-sizing of the equipment.
Another object of the present invention is to provide a solution purification method for a copper electrolyte which can effectively remove impurities with small-sized equipment.
Another object of the present invention is to provide a solution purification method for an electrolyte where Sb and Bi are efficiently adsorbed to a chelate resin, washing of the chelate resin and elution of Sb and Bi are efficiently performed, and the quantity of a washing processing solution is reduced, while an eluate containing high concentration Sb and Bi can be obtained.
Another object of the present invention is to provide a solution purification method for an electrolyte where water washing can be omitted.